Structure of syndiotactic polystyrene thermally crystallized from the glassy state

Vittoria, Vittoria; Filho, A. Ruvolo; Candia, F. De

doi:10.1080/00222349008230380

Cited by 61 publications

(39 citation statements)

References 16 publications

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“…Figure 10 presents the FTIR spectra of sPS and sPS/clay and sPS/clay–CPC hybrids prepared by melt and solution blending. For understanding more clearly the changes caused by the addition of clay or clay/CPC surfactant, the infrared spectrum, ranging from 940 to 820 cm −1 , is highly sensitive to chain packing for the sPS polymorph 24, 26–28. The characteristic infrared bands at 905 and 841 cm −1 originate from the amorphous phase of sPS 21.…”

Section: Resultsmentioning

confidence: 99%

Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

Tseng

Lee

Chang

2001

J Polym Sci B Polym Phys

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We investigated the effects of montmorillonite (clay) on the crystallization kinetics of syndiotactic polystyrene (sPS) with isothermal differential scanning calorimetry analyses. The clay was dispersed into the sPS matrix via melt blending on a scale of 1-2 nm or up to about 100 nm, depending on the surfactant treatment. For a crystallization temperature of 240°C, the isothermal crystallization data were fitted well with the Avrami crystallization equation. Crystallization data on the kinetic parameters (i.e., the crystallization rate constant, Avrami exponent, clay content, and clay/surfactant cation-exchange ratio) were also investigated. Experimental results indicated that the crystallization rate constant of the sPS nanocomposite increased with increasing clay content. The clay played a vital role in facilitating the formation on the thermodynamically more favorable all-␤-form crystal when the sPS was meltcrystallized.

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Section: Resultsmentioning

confidence: 99%

Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

Tseng

Lee

Chang

2001

J Polym Sci B Polym Phys

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“…Although polystyrene (PS), isotactic (iPS) or syndiotactic (sPS), has been the subject of many studies regarding its crystallinity,22–24 lamellar morphology,25–27 chain conformation and orientation,28 and dielectric properties,29–31 there has been limited study from the standpoint of the existence of an RAF. Li and Xue22 obtained a large amount of the RAF of iPS prepared by freeze drying from a dilute solution; the RAF was calculated from the heat capacity increment (Δ C p ) at the glass transition.…”

Section: Introductionmentioning

confidence: 99%

Development of the crystallinity and rigid amorphous fraction in cold‐crystallized isotactic polystyrene

Ince

Cebe

2003

J Polym Sci B Polym Phys

106

117

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The phase structure of crystalline isotactic polystyrene (iPS) has been investigated with temperature-modulated differential scanning calorimetry (TMDSC), wide-angle X-ray scattering (WAXS), and Fourier transform infrared (FTIR) spectroscopy. Quenched amorphous samples have been cold-crystallized at 140 or 170°C for various crystallization times. The degree of crystallinity obtained from WAXS, with the ratio of the crystal peak intensity to the total peak intensity, shows excellent agreement with the crystallinity determined from TMDSC total heat flow endotherms. For the first time, FTIR results show that the absorbance peak ratio (I 981cm Ϫ1/I 1026cm Ϫ1) has a linear correlation with the crystalline mass fraction ( c ) for cold-crystallized iPS according to the following relation: I 981cm Ϫ1/I 1026cm Ϫ1 ϭ 0.54 c ϩ 0.16. This relationship allows the crystallinity of iPS to be determined from infrared spectroscopy analyses in cases in which it is difficult to perform thermal or X-ray measurements. On the basis of the measurements of the heat capacity increment at the glass transition, we find that a significant amount of the rigid amorphous fraction (RAF) coexists with the crystalline and mobile amorphous phases in cold-crystallized iPS. The RAF increases systematically with the crystallization time, and a greater amount is formed at a lower crystallization temperature. A three-phase model (crystalline phase, mobile amorphous phase, and rigid amorphous phase) is, therefore, appropriate for the interpretation of the structure of cold-crystallized iPS. The origin of the low-temperature endothermic peak (annealing peak) has been investigated with TMDSC and FTIR spectroscopy and has been shown to be due to irreversible relaxation of the RAF.

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“…Most likely, endotherm 1 represents the melting of the helix phase. But this melting signal is very incomplete, as it overlaps with the recrystallization into the zigzag phase (2). This zigzag phase melts at even higher temperatures (3).…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4][5] The difference in chain packing of the zigzag conformation leads to the R-and -modifications that can be obtained from the melt or from solution. The helical conformation on the contrary can only be formed in the presence of a solvent, [1][2][3][10][11][12][13][14][15][16][17][18][19][20] and this leads to the formation of two different helical phases, the γ-and δ-phases. In addition, the possibility of the formation of two mesophases is reported.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Induced Structural Changes in Syndiotactic Polystyrene/cis-Decalin Systems

et al. 1997

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Phase transformations in solutions of syndiotactic polystyrene in cis-decalin has been investigated by differential scanning calorimetry, wide and small angle X-ray scattering, and Fourier transformed infrared spectroscopy. The in-situ performed experiments enabled identification of the different modifications without solvent removal. Quenching a solution leads to formation of the helical δ-phase. On heating, this phase transforms into the planar zigzag -phase. The transformation of the helical phase (δ) into the planar zigzag ( ) during heating proceeds via a melting-recrystallization process.

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Structure of syndiotactic polystyrene thermally crystallized from the glassy state

Cited by 61 publications

References 16 publications

Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

Development of the crystallinity and rigid amorphous fraction in cold‐crystallized isotactic polystyrene

Temperature Induced Structural Changes in Syndiotactic Polystyrene/cis-Decalin Systems

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